Studies of locomotions of aquatic animals have intensified recently because it is realized that evolution usually endowed long-existing creatures with efficient locomotion. However, few commercial products emulate such locomotions. One particularly efficient aquatic animal locomotion is the traveling wave method. Lampreys and water snakes use their whole body and cuttlefishes use their fin-like membranes to form a traveling wave. Liquid trapped in the moving recesses of the wave is carried rearward to obtain thrust.
Examples of the deficiencies of existing commercial products occur in oars and paddle wheels. The return stroke of oars wastes energy since no forward thrust is created by return strokes. In paddle wheels the liquid is not moved in the direction of thrust for part of the propelling cycle, especially in the rear of the paddle wheel.
In all such devices, mover-fluid coupling efficiency is important to make full use of available mechanical power. At the extreme ends of the speed range, the coupling efficiency is lower for paddles, oars, and propellers.
The following describes a mechanically produced traveling wave device emulating natural processes that can be used in marine propulsion and pumping fluid, providing a high efficiency of mover-fluid coupling.